Detectionmediumtest

Explorer Process Tree Break

Detects a command line process that uses explorer.exe to launch arbitrary commands or binaries, which is similar to cmd.exe /c, only it breaks the process tree and makes its parent a new instance of explorer spawning from "svchost"

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Launch

Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)Created Sat Jun 29Updated Fri Oct 31949f1ffb-6e85-4f00-ae1e-c3c5b190d605windows

Log Source

WindowsProcess Creation

ProductWindows← raw: windows

CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic

detection:
    # Note: See CLSID_SeparateMultipleProcessExplorerHost in the registry for reference
    selection_factory:
        CommandLine|contains: '/factory,{75dff2b7-6936-4c06-a8bb-676a7b00b24b}' # This will catch, the new explorer spawning which indicates a process/tree break. But you won't be able to catch the executing process. For that you need historical data
    selection_root:
        CommandLine|contains: 'explorer.exe'
        CommandLine|contains|windash: ' /root,'
        # There exists almost infinite possibilities to spawn from explorer. The "/root" flag is just an example
        # It's better to have the ability to look at the process tree and look for explorer processes with "weird" flags to be able to catch this technique.
    condition: 1 of selection_*